Tree girdling with a water jet cutting device

ABSTRACT

A tree girdling technique that uses a water jet cutting device to effect girdling of a tree. After making an undercut in a tree, a girdler is wrapped about a tree at an elevation lower than the undercut and pressurized water with abrasive particles are dispensed from the girdler about the girth of the tree. The dispensing may be done either by rotating a port about the girth or by positioning a series of ports each arranged to direct the pressurized water with abrasive particles to flow in a stream at an oblique angle relative to the inner face of the girdler.

CROSS-REFERENCE TO CO-PENDING PATENT APPLICATIONS

[0001] Priority is claimed from provisional application serial No.60/376,294, filed Apr. 26, 2002.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to cutting around the girth of atree with a water jet cutter that is moved around the tree by an annularguide.

[0004] 2. Description of Related Art

[0005] As recognized by U.S. Pat. No. 3,971,422, conventional practicein tree felling includes the cutting of an undercut or face cut in atree trunk transversely to the intended lay of the felled tree.Typically, the face cut removes a tree trunk section having a roundedsurface with two planar cut surfaces. The undercut extends somewhat lessthan half way through the tree trunk. A second cut, termed a back cut,is made inwardly from the opposite side of the tree and extends inwardlyanywhere from one-half to two-thirds of the trunk diameter, terminatingin close proximity to the undercut at the time the fall commences.

[0006] As recognized by U.S. Pat. No. 4,996,773 tree girdling is aprocess that involves cutting a horizontal strip through the tree barkthrough the Cambian layer around the entire circumference of the tree tointerrupt the flow of water and nutrients. This process usually resultsin the death of the tree.

[0007] The cutting tool used for girdling should be adjusted so that thecambium layer of the tree is completely severed to prevent translocationof water and other nutrients. If the cut is too shallow, then thecambium layer may be not completely severed, which may allow the treetissue to regenerate. If the cut is too deep, then tree may becomeunstable and prone to topple when subjected to high winds. Trees whichare blown down in this fashion often cause damage to surrounding treespecies.

[0008] Hand held power cutting tools have proved to be unsatisfactory incutting or girdling trees. A particularly hazardous drawback of handheld cutting tools that utilize a rotating cutting edge (such aschainsaws) is the tendency for the cutting tool to “kickback” whenjammed. The rotating part of the cutting tool, such as the chain of achainsaw, when stopped or impaired, causes an upward force on the tool.This can be extremely dangerous to the user as the rotating chain orother cutting portion can be forced upwards and back to pivot towardsthe user and can seriously cut the user. The pivot point is generallythe wrist of the hand of the user holding the cutting tool which is theweakest point between the user and the tool. The wrist is generallycontrolled by relatively weak muscle groups which are unable to properlycontrol or prevent “kickback”.

[0009] Manually driven tree girdling tools also suffer from significantshortcomings. Such tools have been unable to achieve a deep enough cutand have resulted in tremendous worker fatigue because of their poorleverage design. Other hand-held tree girdlers have proven to beineffective since they require too much work area around each tree tooperate the tool effectively, thus rendering the tool ineffective indense forest.

[0010] The present inventor observed that the most dangerous part offelling or chopping down the tree is not during the formation of theundercut or face cut in a tree trunk transversely to the intended lay ofthe felled tree, but rather during girdling. Tree girdling or cuttingabout the girth of the tree may last hours depending upon the tree girthdimension. The kickback of the chainsaw that forces the rotating chaintoward the user may seriously injure the user.

[0011] It would therefore be desirable to change the tools andtechniques that are used to fell trees so as to avoid the risk of injuryto those who are engaged in cutting down trees.

SUMMARY OF THE INVENTION

[0012] One aspect of the invention resides in girdling a tree by cuttingthe girth with a water jet of abrasive particles, instead of using achainsaw. A compressor supplies pressurized water that is mixed withabrasive particles to pass through a hose leading to the tree whosegirth is to be cut. The terminal end may be secured to a port of jawsthat are closed about the girth of the tree to be cut. The terminal endmay be moved in a circumferential direction about the tree.Alternatively, a plurality of terminal ends of either different hoses ordifferent branches from the same hose are secured to associated ports inthe jaws about the entire girth of the tree. Pressurized water withabrasive particles passes through each of the hoses eithersimultaneously or successively to cut the entire girth. The direction ofthe cut is at the same oblique angle to the face of the tree being cutat each of the ports. As the cutting progresses, the terminal ends maybe moved in a radial direction to shrink the size of the gap that theflow must travel before impacting the tree girth.

BRIEF DESCRIPTION OF THE DRAWING

[0013] For a better understanding of the present invention, reference ismade to the following description and accompanying drawings, while thescope of the invention is set forth in the appended claims:

[0014]FIG. 1 is a perspective view of a tree and a schematicrepresentation of the present invention in place to cut about aperimeter of the tree.

[0015]FIG. 2 is a perspective view of an enlargement of a portion ofFIG. 1 that shows a belt. legs and a guide rail.

[0016]FIG. 2A is a schematic representation of the belt of FIG. 2.

[0017]FIG. 2B is a schematic representation of legs of FIG. 2.

[0018]FIG. 2C is a schematic representation of a guide rail of FIG. 2.

[0019]FIG. 3 is a schematic representation of a rolling cart with asupporting arm and jaws in accordance with a further embodiment.

[0020]FIG. 4 is a partial view of the belt in accordance with thefurther embodiment.

DETAILED DESCRIPTION OF THE INVENTION

[0021] Turning to the drawing, a tree trunk 10 is felled by first makingan angled undercut 12 using conventional techniques. For instance, achainsaw may be used. Thereafter, a perimeter cut 14 is made about aperimeter or girth of the tree trunk 10 at an elevation below the angledundercut 12 by employing a cutting device that uses a water jet toeffect the cutting with pressurized water and abrasive particles.

[0022] In accordance with one embodiment, a belt 20 is used to hold aterminal end of the cutting device. The belt 20 is moved about thecircumference of the tree trunk and thus the terminal end of the cuttingdevice is likewise moved with the belt. Such movement is done byconnecting the belt 20 to collapsible legs 22 that have wheels 24 on aguide rail 26 running about the tree trunk on the ground that forms aloop encircling the tree trunk. A hose 28 delivers the pressurized waterwith abrasive particles through a belt port 60 to cut the tree. Acompressor 30 supplies the pressurized water.

[0023] A terminal end of the hose 28 is secured to the belt port 60 withany conventional technique for securing a hose to an opening. Theabrasive particles may be sand or metallic filings or fragments.

[0024] As best seen in FIG. 1, the compressor 30 is preferably spacedfar enough away from the tree so that when the tree topples, the treewill not fall on the compressor 30. The same compressor 30 may be usedto supply a flow of pressurized water with abrasive particles tomultiple water jets via multiple hoses by supplying the flow eithersimultaneously to each of the hoses or in a successive manner to each.Any conventional cutting device that supplies pressurized water withabrasive particles that cuts wood may be used. If the pressure availablefrom the compressor is too low to enable cutting simultaneously fromeach of the hoses, then the cutting needs to be done by sending thepressurized water with abrasive particles to the hoses in succession sothat the pressure level delivered is sufficient for wood cutting.

[0025] The belt 20 may have an external face (facing outwardly) made ofmade of a metal alloy and an inner face (facing inwardly) made of aceramic cushion. The belt consists of a plurality of segments 32connected to each other in succession by hinge pins 34. This allows thebelt 20 to be better fitted about the girth of the tree by allowingadjustment of the belt. Leg hooks 36 are provided at spaced intervals oneach section to connect with respective ones of legs 22.

[0026] Each leg 22 has an upper part 40 and a lower part 42 and akneecap 44 between the upper and lower parts. The kneecap 44 ispivotally connected to the upper part 40. The kneecap 44 is configuredto maintain the upper part 40 in a position suited for making theperimeter cut with the terminal end of the hose 28 as long as theperimeter cut has not been completed. Once the perimeter cut is done,however, the kneecap 44 releases the upper part 40 so as to allow theupper part 40 to pivot about the kneecap 44 and fall downwardly closerto the guide rail 26.

[0027] The lower part 42 is not foldable and supports the wheels 24,which are double wheels that run on the guide rail 26. The automaticfolding of the upper part 40 is done to move the belt 20 away from thetree severing area just in case the stump of the cut tree falls in thevicinity of where the belt was located during the cutting operation.

[0028] The automatic folding may be triggered in any of a variety ofdifferent techniques. Sensors may be used to detect when the pressurizedwater with abrasive particles that emerges from the terminal end of thehose 28 clears the perimeter cut already made so as to indicate that theperimeter cut is complete. Such sensors may send signals back to thecompressor 30 to stop sending pressurized water with the abrasiveparticles through the hose 28. Such signals may also be used to triggerthe kneecap 44 to release the upper part 40 from its position so as toallow the upper part 40 to fall.

[0029] Alternatively, the kneecap 44 itself may be powered by divertingthe pressurized water (preferably without the abrasive particles) to itso that when the pressurized water is present, the kneecap 44 isoperative. The kneecap 44 may be operative either hydraulically from thepressurized water or by a motor, to maintain the upper part 40 in theproper position for the water jet terminal end or cutting head to effectthe perimeter cut.

[0030] Once the pressurized water fails to be diverted to the kneecap44, as would be the case when the compressor 30 stops sendingpressurized water, the upper part 40 falls. That is, the absence of suchpressurized water causes the kneecap 44 to no longer maintain the upperpart 40 in the proper position, allowing the upper part 40 to falleither by its own weight or under a spring bias (if springs areprovided). Indeed, a separate locking mechanism may be provided to lockthe kneecap 44 is place when pressurized water is present and to releasethe kneecap when no pressurized water is present (either at the kneecapor emerging from the terminal end or cutting head of the water jetcutting device).

[0031] The guide rail 26 is anchored to the soil with metallic claws 50on either side of the double track. The metallic claws 50 are held inplace beneath metallic U profiles 52, which are also metallic such asmade from steel bar. A pair of metallic claws 50, one on the inner sideof the guide rail 26 and the other on the outer side of the guide rail26, are connected to each other with a link 54. The link is preferablymetallic such as made from steel bar.

[0032] A hydraulic drive may be used to turn axles of one or more of thewheels 24 to drive the belt and therefore move the water jet cuttingdevice discharge around the girth of the tree. The hydraulic drive isdriven by the pressurized water from the compressor 30 used to power thewater jet. The water jet is connected to the belt at a port 60 and theweight of the device may rest on the ground.

[0033] As compared with conventional tree girdling techniques usingchainsaws, the time spent by a labor force in cutting down multipletrees can be significantly lowered by using the belt and water jetcutting device of the present invention. Each tree would have its ownguide in place about the tree trunk to support the discharge of theassociated water jet cutting device. Thus, the only time spent by thelabor force involves forming the undercut and then setting up the beltinto its position about the girth of the tree trunk and connecting theassociated water jet. When done, the labor force can turn its attentionto the next tree to be cut, while activating the water jet to cut thetree girth from a safe distance.

[0034] The setup is as follows. The guide rail 26 is placed on theground to encircle the tree trunk to form a loop. The guide rail 26 issecured into the ground with metallic claws 50. The belt 20 is wrappedabout the girth of the tree by adding belt sections 32 as necessary tocomplete circumference of the girth. The legs 22 are secured to the leghooks 36 and to wheels 24. The guide rail 26 engages with the wheels 24.The terminal end of the hose 28 is connected to the belt port 60 so thatwhen the pressurized water with abrasive particles emerges through thebelt port 60, it flows at an angle that is oblique to the inner face ofthe belt 20. The hose 28 of the compressor 30 is attached to theterminal end or cutting head of the water jet.

[0035] The water supply for the compressor 30 may be any water source,which should be readily available in a forest area such as a stream orriver. The water may need to be purified, which may be done withconventional filtering equipment. During the course of operating of thewater jet cutting device, the pressurized water emerging may miss thetrunk of the tree and strike the inner face of the belt 20. For thisreason, the inner face of the belt 20 is made of a ceramic material thatis more resistance to the impact of the pressurized water striking itthan is the case for the metal alloy. Such an arrangement extends thelife of the belt 20.

[0036] As an alternative, the belt 20 may be replaced by two beltsegments 32. The first belt segment holds the hose 28 and the secondbelt segment is arranged to be in the path of were the water jet maystrike if it clears the cutting area of the tree. The two belt segmentsmay be connected to-each other by wire or by any suitable link.

[0037] Turning to FIGS. 3 and 4, a further embodiment is shown that doesaway with the need for guide rails 26. Instead, a rolling cart 70 isused that supports an arm 72 from which extend two jaws 74. Allnecessary wires, pipes or hose 28 run through the arm 72. The jaws 74have lateral openings 76 for receiving links of the belt 20 or beltsegments 38 to firmly hold them in place. Each of the belt segments 38may carry its own belt port 60 that is fitted with its own terminal endof a branch of the hose 28.

[0038] The jaws 74 are pivotally joined together at the end of the arm72 and move swing about the pivot towards or away from each other. Eachjaw may be curved because of pivots 34 to facilitate being wrappedaround a portion of the girth of a tree trunk, that is, each jaw mayconform in shape to a curvature of the girth of the tree. The beltsegments 38 that make up the jaws, however, may each remain flat withoutcurvature because the pivot 34 between them adapts to the curvature ofthe girth of the tree, particularly where the widthwise dimension of thebelt segments 38 is small.

[0039] Pressurized water with abrasive particles may reach multiple beltports 60 by employing a manifold to distribute the flow to each of thebelt ports 60. The manifold has hose segments that branch off to connectwith each of the belt ports 60. Each of the belt ports angles thecutting head of end of the water jet cutting device preferably upwardlyat an oblique angle so that cut material is forced laterally withoutbeing blocked by the belt. To provide some rigidity to the jaws wherethe belt segments 38 are to some extent flexible, metal alloy links 62are provided on the opposite side of the belt segments 38 from which isattached the pivots 34. Thus, the metal alloy links 62 form an innerfacing surface of the jaws and may provide a substantially flat surface.

[0040] As an alternative to the use of a manifold, separate hoses 28 maybe used. In either case, the pressurized water with abrasive particlesis sent to each hose or hose segment, as the case may be, eithersimultaneously if sufficient water pressure is available or insuccession. If done in succession, the flow to each hose or hosesegments is either open or closed at any given time by valves (notshown). Such valves are controlled to open or close in response toinstructions from the controller.

[0041] Each terminal end of the hose 28 may be movable relative to thecut portion of the tree so that it may be moved closer to the center ofthe tree. Such movement is useful to avoid dissipation of thepressurized water as it travels toward the tree after emerging from thehose. Detectors or a time clock may be used to trigger movement of thehose after cutting has commenced.

[0042] For instance, if based on the species of tree being cut and itsdiameter, the amount of time needed to cut the tree by a proper amountfor effective girdling may have been observed, measured or computedpreviously and the same time duration may be applied again. After theelapsed time has passed, it is likely that an appropriate amount ofcutting has occurred.

[0043] Alternatively, as the gap widens between the terminal end of thehose and the tree trunk, the pressurized water with abrasive particleswill have further to travel to reach wood to effect cutting. If thedistance is too great, the impact felt by the tree trunk from suchpressurized water with abrasive particles reduces due to dispersion.Such lessened impact effects may be detected with sensors, which arearranged to transmit appropriate signals to a controller [not shown]. Inresponse to the signals signifying that the distance is too great, thecontroller sends instruction signals to a driver to drive the terminalends of the hoses or hose segments closer in a radial direction to thecenter of the tree trunk.

[0044] The movement of each terminal end of the hose 28 may be carriedout by a driver of any conventional technique, such as with a motor orhydraulic drive. Such drivers may operate in response to instructionsfrom a controller.

[0045] The controller determines whether there is a need to move theterminal end of the hose 28 based on signals from the sensors and, ifsuch a determination is affirmative, instructs the driver to move theterminal end of the hose 28 inwardly and the sensing continues. Ifnegative, no movement instructions are sent. Both the driver and thecontroller are powered from electricity supplied through the wires inthe arm 72 and/or by hydraulic pressure supplied through pipes in thearm 72.

[0046] For the sake of convenience, the belt 20 or jaws 74 that wraparound the girth of the tree will be referred to as a girdler. Also, thehose 28 or hoses may be considered a tubular structure. While theforegoing description and drawings represent the preferred embodimentsof he present invention, it will be understood that various changes andmodifications may be made without departing from the spirit and scope ofthe present invention.

What is claimed is:
 1. A tree girdling apparatus, comprising: a girdlerhaving at least one port and an inner face; a source of pressurizedwater with abrasive particles; and a tubular structure that conveys thepressurized water with abrasive particles from the source to the atleast one port and arranged to direct the pressurized water withabrasive particles to emerge in a stream from the at least one port atan oblique angle relative to the inner face of the girdler.
 2. Anapparatus as in claim 1, wherein the girdler includes two jaws movablebetween an open position and a closed position, the two jaws configuredand arranged to be moved toward each other to reach the closed positionand to be moved away from each other to reach the open position, thejaws carrying the port.
 3. An apparatus as in claim 1, furthercomprising: a rail forming a loop; wheels on the rail so as to allow thewheels to move along the rail in response to forces being exerted; andlegs connecting the wheels with the belt for moving the girdler aboutthe loop.
 4. An apparatus as in claim 2, further comprising at least onelocking device responsive to delivery of the pressurized water tomaintain the girdler at a elevation in the closed position and beingresponsive to cessation of delivery of the pressurized water to free thegirdler to enter into the open position.
 5. An apparatus as in claim 1,wherein the girdler has a curvature, the at least one port being aplurality of ports, the tubular structure including a plurality of hoseseach being connected to associated ones of the ports, each of the hosesbeing arranged to convey the pressurized water with abrasive particlesfrom the source to associated ones of the ports.
 6. An apparatus as inclaim 1, further comprising a compressor as the source of thepressurized water.
 7. An apparatus as in claim 1, wherein the inner faceof the girdler is a ceramic cushion.
 8. An apparatus as in claim 1,further comprising an arm that supports the girdler.
 9. An apparatus asin claim 1, wherein the inner face of the girdler is configured toconform substantially to a curvature of the girth of the tree.
 10. Amethod of tree girdling, comprising: arranging a girdler about a girthof a tree, the girdler having at least one port and having an innerface; and conveying water with abrasive particles from a source via atubular structure to at least one port so that the water with abrasiveparticles emerges in a stream from the at least one port at an anglethat is oblique to the inner face of the girdler.
 11. A method as inclaim 10, further comprising moving the girdler along a rail, the railforming a loop.
 12. A method as in claim 10, further comprising drivingthe girdler on the rail in response to delivery of the pressurizedwater.
 13. A method as in claim 10, wherein the girdler includes twojaws, further comprising moving the two jaws from an open position to aclosed position about the girth of the tree by moving the two jawstoward each other.
 14. A method as in claim 10, further comprisingmaintaining the girdler at a elevation in response to delivery of thepressurized water and freeing the jaws to move to the open position fromthe closed position in response to cessation of delivery of thepressurized water.
 15. A method as in claim 10, wherein the arrangingincludes hinging a plurality of sections of the girdler to each other toform a ring, engaging wheels on the rail and extending legs between thewheels and the girdler.
 16. A method as in claim 10, further comprisingarranging a compressor to provide the pressurized water, and extending ahose between the compressor and the girdler to convey the pressurizedwater.
 17. A method as in claim 10, further comprising cushioning thegirdler with a ceramic cushion on an inside face of the girdler.
 18. Amethod as in claim 10, further comprising supporting the girdler with anarm.
 19. A method as in claim 10, further comprsing substantiallyconforming the inner face of the girdler is configured to a curvature ofthe girth of the tree.